diff --git a/haystack/pipelines/config.py b/haystack/pipelines/config.py
index 8e1345a11..a423171d7 100644
--- a/haystack/pipelines/config.py
+++ b/haystack/pipelines/config.py
@@ -21,7 +21,7 @@ from haystack.errors import PipelineError, PipelineConfigError, PipelineSchemaEr
 logger = logging.getLogger(__name__)
 
 
-VALID_INPUT_REGEX = re.compile(r"^[-a-zA-Z0-9_/\\.:]+$")
+VALID_INPUT_REGEX = re.compile(r"^[-a-zA-Z0-9_/\\.:*]+$")
 VALID_ROOT_NODES = ["Query", "File"]
 
 
@@ -97,10 +97,7 @@ def read_pipeline_config_from_yaml(path: Path) -> Dict[str, Any]:
         return yaml.safe_load(stream)
 
 
-JSON_FIELDS = [
-    "custom_query",  # ElasticsearchDocumentStore.custom_query
-    "custom_mapping",  # ElasticsearchDocumentStore.custom_mapping
-]
+JSON_FIELDS = ["custom_query"]  # ElasticsearchDocumentStore.custom_query
 
 
 def validate_config_strings(pipeline_config: Any):
diff --git a/test/pipelines/test_pipeline.py b/test/pipelines/test_pipeline.py
index 2f29e8b62..0d3e09eab 100644
--- a/test/pipelines/test_pipeline.py
+++ b/test/pipelines/test_pipeline.py
@@ -687,9 +687,6 @@ def test_validate_pipeline_config_component_with_json_input_valid():
     validate_config_strings(
         {"components": [{"name": "test", "type": "test", "params": {"custom_query": '{"json-key": "json-value"}'}}]}
     )
-    validate_config_strings(
-        {"components": [{"name": "test", "type": "test", "params": {"custom_mapping": '{"json-key": "json-value"}'}}]}
-    )
 
 
 def test_validate_pipeline_config_component_with_json_input_invalid_key():